This K23 application will provide the candidate with the scholarly training, mentorship, and support necessary to develop an independent line of theory-driven research examining important variables that contribute to social development following traumatic brain injury (TBI) in young children. This objective will be accomplished through a five-year training program and associated research activities. The training program has five objectives. First, the candidate will expand her knowledge of the neural basis of social development to understand how early neurological injury impacts subsequent development. Second, she will develop expertise in research paradigms and theories traditionally used by developmental psychologists that can be applied to design novel and innovative studies of clinical populations such as pediatric TBI. Third, the candidate will increase the sophistication of her skills in several key areas of design and analysis. Fourth, she will enhance her scientific writing skills. Fifth, she will receive additional training in the responsible conduct of research. Her co-primary sponsors are established researchers in the area of neurobehavioral outcomes and family adjustment following pediatric TBI. Additional mentors will include experts in areas directly relevant to the training objectives and research plan. The proposed research plan is designed to examine short- and long-term social outcomes and to test a model of the development of social competence following TBI during the preschool years. Deficits in social competence, social information processing (SIP) skills, and core neuropsychological abilities are predicted outcomes of preschool TBI. The theoretical model to be tested rests on the assumption that TBI causes dysfunction of the brain networks responsible for the development of neuropsychological abilities needed for effective SIP and good social adjustment. The model proposes that the SIP deficits are at least partially responsible for the emergence of poor social competence. The influences of pre-injury child characteristics, injury parameters, and pre- and post-injury parenting practices will also be investigated to isolate the effects of TBI on social competence. The research study capitalizes on the unique resources and the rich developing database of a NIH (NICHD/NCMRR) funded project on family adaptation and child recovery following preschool TBI led by the co-primary sponsors for this proposal. This project will launch the candidate's research career in investigating the mechanisms by which TBI in young children leads to social difficulties and provide a basis for designing interventions to improve social competence.